Formation mechanism of SH guided wave in weld seam

Abstract

Shear horizontal (SH)-guided wave detection of weld seams is a new type of weld detection technology. To better apply SH-guided waves to weld detection, it is necessary to study the formation mechanism of SH-guided waves and to identify weld structures suitable for SH-guided wave detection. Here, we used the theory of peridynamics as well as the reflection and refraction of SH-guided waves in different media. Theoretical analysis suggested that the formation of an SH-guided wave is related to the incident angle of the guided wave, and the formation of SH-guided waves is related to the weld height and the weld interface. The influence of different weld heights and weld interfaces on the formation of SH-guided waves was studied by numerical simulation. We concluded that the weld height is beneficial to the formation of the guided wave because the strength of guided wave in weld seam and steel plate can reflect the refraction and reflection characteristics of the SH wave. More energy is trapped in the weld with increasing weld height, and the radiation rate of SH-guided waves linearly decreases. Higher welds will disperse the SH-guided waves and confuse the signals. This makes the echo subtle and is not conducive to the detection of weld defects. Therefore, we concluded that weld heights over 5% of the weld width are more conducive to detection of weld defects. After analysis of the weld interface, we concluded that the radiation rate of SH-guided waves in a U-type interface and V-type interface are much higher than those a type II interface: These are not conducive to the formation of weld-guided waves and lead to low sensitivity for SH-guided wave detection.